Nucleic Acids

Intermolecular Forces

2nd Law of Thermodynamics

Integration of Metabolism

Recombination and Mutation

Because the unwinding of the double helix occurs abruptly at a certain temperature, the process is referred to as 'melting'. The higher the GC percentage, the higher the melting temperature. The melting temperature can be lowered by the addition of urea or formamide.

Urea and formamide are the two most common agents which accomplish chemical denaturation. These substances act to disrupt the hydrogen bonding between the nitrogen bases. Usually some combination of formamide, urea, and heat is employed, for example, in sample preparation for denaturing electrophoresis of DNA, an important separation technique for analysis or purification in the molecular biology laboratory.